Obesity is a risk factor for multiple health problems that has proved markedly difficult to treat. The present study examines the feasibility of weight gain prevention as an alternative method for addressing obesity as a public health problem. Pilot studies have established that normal weight volunteers can be successfully recruited for a weight gain prevention intervention and that a program utilizing a combination of educational and incentive strategies may be effective in preventing weight gain over one year. The present study extends this research by increasing the size and diversity of the sample, increasing the duration of treatment, and experimentally evaluating the individual and combined efficacy of the main intervention components (i.e., education and incentives). A total of 1,200 adults (20-45 years old) will be studied. Eight hundred will be volunteers recruited by newspaper ad who are interested in weight control. These will be randomized to one of four groups in a 2 x 2 design (no-treatment, education, incentives, and education plus incentives). Four hundred additional individuals will be recruited from the community who are not specifically interested in weight control. These will be randomized to either education or no-treatment. The study will be conducted through local health departments and will be evaluated over three years. Outcome measures will include body weight, eating and exercise habits, and various psychosocial variables. The study design provides an opportunity to examine predictors of weight change in volunteer and nonvolunteer samples of non-obese individuals as well as to test the hypothesis that low cost intervention strategies will be successful in reducing expected increases of weight with age in these groups.